Pneumatic valves are one of many components of a system that controls the flow of a fluid through the system. Pneumatic valves are control devices that are powered by pressurized fluid, normally air. In many circumstances, pneumatic pressure is supplied to the driving portion of the valve from a pressure source. The driving portion of the valve transforms pneumatic pressure into mechanical power for operating or actuating a control mechanism in a supply line, duct, or pipe. The control mechanism may be an isolation valve having only two positions, open and closed, where the open position allows flow to pass and the closed position stops flow. The control mechanism may also be a control valve that is capable of modulating flow of the fluid it is controlling. For example, the control valve may allow fluid to pass in increments of one percent from zero percent to one hundred percent.
There are many different types of control mechanisms that may be connected to a pneumatic driver, such as ball valves, butterfly valves, or gate valves. These valves may be used in many applications such as pneumatic tools, industrial processes, and aircraft environmental control systems. In one example, a pneumatic valve may be part of a butterfly valve control mechanism operated by a pneumatic driver in a bleed system of an environmental control system of an aircraft. In this example, pneumatic pressure may be taken from a high pressure supply line to ultimately control a butterfly valve which modulates the flow of pressurized air through a duct, tube, or pipe in an aircraft environmental control system. In this example, careful consideration must be made of flow rates and pressures, as an environmental control system is critical to the operation of the aircraft.